In the months before the 2006 World Cup, economists at Dutch bank ABN AMRO produced a detailed report analyzing soccer's distinct and quantifiable impact on a country's economy and forecast that an Italian victory would be most beneficial to financial markets.

“An Italian victory would make consumers and producers more confident, which would translate into higher consumption and investment,” the report said. “It would also help Italy to improve its image, which is good for exports.”

Italy won the most coveted championship in sports that summer. And after zero economic growth for 2005 and the first half of 2006, Italy's consumer confidence spiked within days of the dramatic shootout win against France. By the following year its gross domestic product had grown nearly 2 percent — more than the bank's economists had projected.

“Soccernomics,” they call it.

Figure that the boys at ABN AMRO are rooting for Mexico tomorrow when it hosts the United States at Estadio Azteca.

At stake are vastly improved prospects at qualifying for the 2010 World Cup, plus a chance for the Americans to win on Mexican soil for the first time in history, plus bragging rights between regional rivals.

Plus a potentially profound effect on the entire Mexican economy.

The bigger the game, the bigger the impact, and tomorrow's 1 p.m. PDT kickoff is arguably the biggest for Mexico in two decades given the fragile state of its qualifying campaign and equally fragile state of its economy.

“It's important first to win as a football team,” said Jorge Vergara, the owner of iconic Mexican club Chivas of Guadalajara, “and secondly because of the attitude of the whole country. What happens in football is very integrated into the economic life of the Mexicans. They're going to be depressed, if we lose, for quite a long time. If we win, productivity goes up.

“Why? Because football is a reflection of Mexican life. The Mexican national team, if it goes wrong, your life goes a little bit bad.”

It is a phenomenon that is well-documented and generally accepted by economists across the world, and largely foreign to Americans.

Sports fans here are focused on professional leagues and not flag-waving, chest-thumping international competition. And soccer in America is still viewed by many as a grass-roots enterprise, with girls in ponytails, orange slices at halftime and parents sitting in beach chairs on the sideline. The game ends, the kids get their snacks and everyone merrily piles into the minivan for the ride home. Some youth leagues don't even keep score.

In Mexico, like most other soccer-obsessed countries, the sport's tentacles reach deep into the national psyche — influencing mood and disposition, which in turn influence consumer confidence and worker productivity, which in turn influence the economy as a whole.